The RNIB has shed 230 staff over the last financial year and a further 350 jobs are at risk, Third Sector has been told.
The sight-loss charity has yet to publish its accounts for the year ending 31 March 2018, but a spokeswoman said it had 1,674 employees last month – 230 fewer than 12 months earlier.
And a source at the charity told Third Sector that the RNIB had begun a consultation on the future of another 350 positions in a bid to become more sustainable in the long term.
The charity, which reported a £12.6m deficit in the year ending 31 March 2017, said it expected to report a small surplus in 2017/18.
A spokeswoman for the RNIB declined to comment on the number of jobs that could be at risk under the current consultation.
"Like any charity, we have to make careful and sometimes difficult decisions to ensure our long-term sustainability and make the most of the resources we have," she said.
"Conversations about the future of a number of roles at the RNIB are ongoing as we restructure to deliver the best possible support to blind and partially sighted people.
"Several consultations are open across the organisation and as a result a number of jobs are at risk.
"We are working closely with the unions and taking steps to minimise the number of redundancies, including a programme of voluntary redundancy and redeployment."
Eliot Lyne, the charity’s interim chief executive, told Third Sector that the accounts for 2017/18 would show the charity's two-year financial transformation plan, which focuses on controlling costs, was working.
He said the charity was likely to deliver a "small operating surplus" this year. "There has been a substantial turnaround," he said.
Lyne said income was likely to be "slightly lower" than last year's £119m, but expenditure, which rose sharply from £123m to £133m, had been brought down.
"We have reduced some costs, reduced staff numbers and become more efficient in our processes," said Lyne.
The RNIB shed 198 staff in 2016/17, which incurred redundancy and termination costs of £2.2m.
In recent months Ofsted, the regulator for children’s homes and specialist schools, has published a critical inspection report on the RNIB, the Charity Commission has opened a statutory class inquiry and the chief executive, Sally Harvey, has resigned unexpectedly.
Harvey resigned last month after the commission opened a statutory class inquiry into the RNIB and its subsidiary, the RNIB Charity, because of concerns that the charity had "consistently failed to comply with regulations designed to safeguard and protect vulnerable children" at a children's home at the RNIB Pears Centre for Specialist Learning in Coventry, Warwickshire.
Ofsted inspectors visited the home in February and their subsequent report highlighted "widespread systemic failures", ineffectual management systems and "significant concerns with how the safety and welfare of children and young people is promoted".